Cytology: when is enough
A thin needle aspirates cells and fluid rather than a column of tissue, so the method is optimal for assessing the contents of cysts (Bosniak II–III), emptying and cytology of suppurative or hemorrhagic cysts, as well as for rapid confirmation of a metastatic or lymphoproliferative process. The risk of bleeding is minimal, observation - 2-3 hours. Limitation: Cytology does not always distinguish subtypes of kidney tumors or assess tissue structure; if the result is unclear, a core biopsy with histology is performed.
Why is a kidney biopsy necessary?
A biopsy is the only way to find out the exact nature of the changes in the kidney. In nephrology, it is performed for glomerulonephritis, nephrotic syndrome, unexplained renal failure and protein in the urine in order to select treatment according to the morphological type. In urology - for kidney tumors, when the diagnosis on CT is unclear, before ablation or active surveillance of small formations, when lymphoma or metastasis is suspected, and in patients for whom surgery is contraindicated.
Security
Under ultrasound guidance with a thin needle, the risk of complications is low: a small hematoma occurs in 5–10% and resolves on its own, significant bleeding occurs in less than 1%. For prevention, blood thinning medications are stopped a week in advance, blood pressure and coagulation are monitored, and after the biopsy the patient lies for 6-12 hours and is observed in the clinic. A control ultrasound is performed a day later.
